Asthma is one of the most common chronic illnesses and it disproportionately affects disadvantaged populations residing in urban areas. Mouse allergen exposure, in particular, appears to play a critical role in the urban asthma epidemic for several reasons. (1) Mus m 1, the major mouse allergen, is found in 95% of inner-city homes, and is found in 100-fold higher concentrations in inner-city homes than in suburban homes. (2) As many as 25-50% of children with asthma living in urban areas have evidence of IgE-sensitization to mouse, making them susceptible to mouse allergen-triggered asthma symptoms. (3) Household mouse allergen exposure is associated with more symptoms days, more rescue medication use, and more asthma-related health care use among IgE-sensitized children with asthma, independent of cockroach sensitization and exposure status. For these reasons, an environmental intervention targeted at reducing household Mus m 1 levels is a promising approach to reducing asthma morbidity in urban populations. Preliminary evidence indicating that a mouse allergen-targeted environmental intervention (MA-EI) is efficacious in reducing Mus m 1 levels provides the final piece of background data to support the hypothesis that a MA-EI will reduce asthma morbidity in mouse-sensitized individuals with asthma. To test this hypothesis, we propose conducting a multi-center, randomized clinical trial of MA-EI at three major urban centers with high prevalence rates of asthma and mouse sensitization, and high household Mus m 1 levels. The specific aims are: (1) To evaluate the efficacy of a mouse allergen-targeted EI in reducing Mus m 1 exposure in mouse-sensitized children and young adults with asthma living in urban areas, and (2) To evaluate the efficacy of reduction of mouse allergen exposure in reducing asthma morbidity. We will assess symptom days as the primary outcome variable, in addition to rescue medication use, asthma-related health care use, exhaled nitric oxide levels and pulmonary function as secondary outcome variables. For the planning phase of this clinical trial, we propose the following aims: (1) Finalization of the study protocol, development of the manual of procedures and the data safety monitoring plan, and completion of the IRB approval process, (2) Development of the data management plan, and (3) Establishment of community advisory boards. The findings from the clinical trial will lend critical insight into the impact of household mouse allergen exposure on urban populations with asthma, and directly inform public health strategies to reduce the inner-city asthma burden. [unreadable] [unreadable] [unreadable]